In the case of direct injection of fuel into the combustion chamber of an internal combustion engine, the problem arises that deposits in the form of fuel deposits or soot particles occur in the region of the injection valve tip projecting into the combustion chamber. These can have a negative effect, on the one hand, on the emissions characteristics of the internal combustion engine and also, on the other hand, on the operating parameters of the injection valve.
To overcome this problem, DE 199 51 014 A1, for example, discloses the application of coatings at the combustion-chamber end of the injection valve, said coatings being used to bring about catalytic conversion or combustion of the unwanted deposits.
Even when such catalytic coatings are used at the combustion-chamber end of the injection valve, however, there is the additional problem during the operation thereof that the temperatures which occur in the region of the catalytic coatings during normal engine operation are often insufficient to ensure effective progress of the desired catalytic reactions, and, in particular, the “light off temperature” of the catalytically active layer is often not reached. As a consequence, it may happen that the special catalytic coating used does not achieve the intended effect and, as a result, impairments of valve operation and also increased emissions from the internal combustion engine may occur owing to the residual fuel and soot particle deposits.
Given the above background situation, the inventors herein provide an injection valve for injecting fuel into the combustion chamber of an internal combustion engine which allows increased elimination of unwanted deposits on the combustion chamber end section of the injection valve and hence an improvement in the operating behavior of the injection valve and in the emissions characteristics of the internal combustion engine during the operation of the internal combustion engine.
Accordingly, an injection valve for injecting fuel into a combustion chamber of an internal combustion engine comprises a valve seat, a valve element, at least one injection opening formed in the valve seat and leading to the combustion chamber, the at least one injection opening opened or closed by a stroke motion of the valve element, a catalytic coating provided in a region of the injection valve which faces the combustion chamber, and at least one protuberance which is elongated in a direction of the combustion chamber and projects into the combustion chamber.
In this way, the injection valve of the present disclosure allows improved elimination of deposits (e.g. fuel) in the region of the injection valve tip projecting into the combustion chamber and hence also more favorable emissions characteristics of the internal combustion engine by way of more efficient use of existing catalytic coatings.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.